Cerebral palsy (CP) is the most common childhood motor disability. It is caused by a brain lesion before or immediately after birth. It is often described as an “umbrella term” comprising several different syndromes. CP is considered as one of the most severe disabilities in childhood and has a strong impact on families and children themselves. Moreover cerebral palsy makes heavy demands on health, education and social services. The life expectancy of children with cerebral palsy is increasing worldwide, even among children with a severe level of impairment.
The majority of children with CP develop muscle spasticity early in childhood which may impact their ability of performing voluntary movement. Furthermore, muscular changes that greatly interfere with movement typically develop early and may result in joint deformities and reduced range of movement. These changes usually require surgical intervention at some point during childhood to improve joint mobility.
Spasticity is also commonly associated with other disorders or injuries such as spinal cord injury, multiple sclerosis, stroke and traumatic brain injuries.
For assessment of muscle spasticity two subjective scales (and methods) are normally used: The Modified Ashworth Scale (MAS) and the Modified Tardieu Scale (MTS). None of them are known to be objective and sufficiently reliable. Since the diagnosis and the following treatment are mainly or partly based on these scales there is a risk of wrong treatment. Studies conclude that there is a need of simple instruments, which provide a reliable quantitative measure with a low inter-rater variability.
WO 2008/121067 discloses a system to evaluate spasticity in a movable extremity, wherein a joint is passively extended at two constant velocities, slow and fast. The slow velocity movement is performed without any reflex contribution, and the fast velocity movement is performed with reflex contribution.
WO 2006/102764 discloses a method for measurement of spasticity in a patient by recording an EMG signal while the limb is being moved at a variety of angular velocities.
US 2007/027631 discloses an apparatus and a method for evaluating spasticity in a movable extremity. The apparatus includes an accelerometer, a gyroscope, and a sensor adapted for quantifying force or pressure. The method includes moving the extremity through a range of motion about an axis of rotation. Measured parameters are transmitted to a data processor which processes the data to generate information that characterizes the hypertonic condition.